From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 62B91C001DE for ; Fri, 21 Jul 2023 18:53:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231226AbjGUSxF (ORCPT ); Fri, 21 Jul 2023 14:53:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46552 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231210AbjGUSxE (ORCPT ); Fri, 21 Jul 2023 14:53:04 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE0F530CA; Fri, 21 Jul 2023 11:53:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=r7HKb0fHKAzqTvjH4XFG87Ln9mhascjsc5GVXDtG5p0=; b=iMKuGzkflbdlrFkVAjStdw2Je5 9kHIxeM+r1V0Yn0ulE3UYkPmNrg8KIegNMAfErN0GSTjejkOqn+8nH4FD11aIYTl4FsXdNv803aBo gzjhnriyNiotaaCyuAcmqn65Mh42ZcG78tdz2OFKdRUIsuAJ6TOBzlA0DRgVYG+nowv9V0MgAe4fB hkVVUF6MRXdgth7Yhuw32q3XQLEinsbxbHFcOdAdnJk9C5uGCNotMVqvCNInv5DhpsBJPepJDdVAX OHwNbfbW6kapWN1CQ8d1CwVlb7Uk/bjgcPC1Z5YgwSkhLRZwZyfOalWNMj0TWGVIevIdN8Q97t9Yz Eag+OfGg==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1qMvF8-001NGA-OP; Fri, 21 Jul 2023 18:52:47 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 42BF4300346; Fri, 21 Jul 2023 20:52:46 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 0EA6C315B37C6; Fri, 21 Jul 2023 20:52:46 +0200 (CEST) Date: Fri, 21 Jul 2023 20:52:46 +0200 From: Peter Zijlstra To: Arnd Bergmann Cc: Thomas Gleixner , Jens Axboe , linux-kernel@vger.kernel.org, Ingo Molnar , Darren Hart , dave@stgolabs.net, andrealmeid@igalia.com, Andrew Morton , urezki@gmail.com, Christoph Hellwig , Lorenzo Stoakes , linux-api@vger.kernel.org, linux-mm@kvack.org, Linux-Arch , malteskarupke@web.de Subject: Re: [PATCH v1 02/14] futex: Extend the FUTEX2 flags Message-ID: <20230721185246.GR4253@hirez.programming.kicks-ass.net> References: <20230721102237.268073801@infradead.org> <20230721105743.819362688@infradead.org> <6a49b585-05d0-4b79-b5ab-d710f5d6d598@app.fastmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6a49b585-05d0-4b79-b5ab-d710f5d6d598@app.fastmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Fri, Jul 21, 2023 at 05:47:31PM +0200, Arnd Bergmann wrote: > On Fri, Jul 21, 2023, at 12:22, Peter Zijlstra wrote: > > * futex_parse_waitv - Parse a waitv array from userspace > > @@ -207,7 +207,12 @@ static int futex_parse_waitv(struct fute > > if ((aux.flags & ~FUTEX2_MASK) || aux.__reserved) > > return -EINVAL; > > > > - if (!(aux.flags & FUTEX2_32)) > > + if (!IS_ENABLED(CONFIG_64BIT) || in_compat_syscall()) { > > + if ((aux.flags & FUTEX2_64) == FUTEX2_64) > > + return -EINVAL; > > + } > > + > > + if ((aux.flags & FUTEX2_64) != FUTEX2_32) > > return -EINVAL; > > This looks slightly confusing, how about defining another > FUTEX2_SIZEMASK (or similar) macro to clarify that > "aux.flags & FUTEX2_64" is a mask operation that can > match the FUTEX2_{8,16,32,64} values? Yeah, I had that in an earlier version, but then reconsidered as I didn't want to clutter the uabi with that. But perhaps I over-throught this.